Booster for template controlled truing mechanism



Dec. 25, 1956 w. F. JESSUP 2,775,235

BOOSTER FOR TEMPLATE CONTROLLED TRUING MECHANISM Filed Aug. 22, 1955 4Sheets-Sheet l 3 u j 440 /4 Fl g i Z m9 m7 i A24 /2/ 4 INVENTOR. W/LBURF. JESS BY A T TORNE Y8.

Dec. 25, 1956 w. F. JESSUP 2,775,235

BOOSTER FOR TEMPLATE CONTROLLED TRUING MECHANISM Filed Aug. 22, 1955 4Sheets-Sheet 3 INVENTOR.

W/LEUF? F. JESSUP flTTORNE YS.

Dec. 25, 1956 w. F. JESSUP 2,775,235

BOOSTER FOR TEMPLATE CONTROLLED TRUING MECHANISM Filed Aug. 22, 1955 4Sheets-Sheet 4 INV EN TOR.

W/LBUR F. JESSUP United States Patent BOOSTER FOR TEMPLATE CONTROLLEDTRUING MECHANISM Wilbur F. Jessup, Cincinnati, Ohio, assignor to TheCincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of OhioApplication August 22, 1955, Serial No. 529,827

9 Claims. (Cl. 125-11) This invention relates to truing mechanisms forgrinding machines and more particularly to an improved profile truingmechanism.

One of the objects of this invention is to provide an improved templatecontrolled truing mechanism which will automatically negotiate rises andfalls in the shape of the template including right angle turns.

Another object of this invention is to provide an improved hydraulicallyoperated template controlled truing mechanism.

A further object of this invention is to provide an improved traversingcontrol mechanisin for feeding a template controlled truing tool whichis automatically responsive to changes in resistance to feeding causedby sharp changes in the shape of the template to effect a boostingaction to assist the template in moving the tool when sharp changes indirection are encountered.

Another object of this invention is to provide an improved mechanism forautomatically advancing and retracting a truing tool during its feedingmovement in response to changes in the shape of the template beingfollowed and to cooperatively interrelate said mechanism with thefeeding mechanism.

Other objects and advantages of the present invention should be readilyapparent by reference to the following specification, considered inconjunction with the accompanying drawings forming a part thereof, andit is to be understood that any modifications may be made in the exactstructural details there shown and described, within the scope of theappended claims, without departing from or exceeding the spirit of theinvention.

In the drawings in which like reference numerals indicate like orsimilar parts:

Figure 1 is an elevational view of a grinding machine embodying theprinciples of this invention.

Figure 2 is an end view of the truing mechanism as viewed on the line2-2 ofFigure 1.

Figure 3 is a plan view of the truing mechanism as viewed on the line3-3 of Figure 1.

Figure 4 is a sectional view through the truing mechanism as viewed onthe line 4--4 of Figure 2.

Figure 5 is a diagrammatic view of the hydraulic control circuit.

Figure 6 is a detail view as viewed on the line 6--6 of Figurel. i

In the grinding of profile work pieces by the infeed grinding method incenterless grinding machines, the grinding wheel is provided with aprofile shape corresponding to the shape to be produced in the work. Theshaping of the grinding wheel is accomplished by means of a truing toolwhich is traversed across the face of the grinding wheel, and as thewheel wears, it is dressed periodically to maintain the accuracyof theshape. This is usually accomplished by utilizing a truing tool connectedto a follower which engages a fixed template so that by traversing thefollower across] the template it determines the movements ofthe tooltoward and from the grinding wheel.

'ice

In the case of templates having very gradual changes in direction it ispossible to maintain the follower in contact with the template by simplespring means, for instance, and the template will thereby cause or forcethe truing tool to move toward and from the grinding wheel as traverseof the template progresses. in cases, however, where the changes in thetemplate are sharp, and especially where right angle shoulders areencountered, it is impossible to utilize this method, especially if itis to be done automatically. It will be obvious that when a right angleshoulder is encountered, the template is helpless to move the follower,and the feeding or traversing movement of the truing tool must bestopped in order to effect the necessary advance or retraction of thetruing tool.

By means of this invention, an auxiliary power means or booster isprovided for assisting: the template in moving the truing tool over thesharp rises and falls of the template, and this means is cooperativelyinterrelated with the traversing mechanism so that the feeding movementi will stop at such critical times.

This is accomplished by providing a power feeding mechanism which isresponsive or sensitive to changes in load resistance to a sufficientextent that the rate of feeding movement will change as the resistancechanges, and automatic means responsive to such changes will apply aboosting force to the follower to assist its movement in whicheverdirection it is supposed to move.

in Figure 1 of the drawings there is shown a grinding machine, indicatedgenerally by the reference numeral 10, having a grinding wheel 11 whichconstitutes a suitable machine for application of the principles of thisinvention. The machine illustrated. is a conventional centerless grinderhaving a bed 12 upon which the grinding Wheel 11 is mounted for powerrotation, and a regulating wheel 13 is mounted in opposition to thegrinding wheel on suitable slides for adjustment toward and from thegrinding wheel. The work, such as the work piece 14, is suitablysupported on a work rest 15 situated between the wheels for holding thework piece in proper grinding relation with respect to the centers ofthe wheels.

This invention deals with the art of grinding profiled work pieces andmore particularly to means for dressing the grinding wheel to a shapecomplementary to the shape to be ground on the work piece. Moreparticularly, this invention deals with grinding shapes which requireangular shoulders to be formed on the grinding wheel, and shapesinvolving right angular shoulders cannot be trued automatically byconventional truing mechanisms, especially those of the templatecontrolled va riety.

In Figure 6 there is shown the extreme condition in which the grindingwheel 11 is provided with annular square ribs 16, 17 and 18 for grindinggrooves 19, 28, and 21 in the work piece 1 3 as well as the cylindricalsurface thereof, and a template 22 shown in Figures 3 and 5 is providedwith corresponding ribs23, 24, and 25 for guiding a follower 26 whichcorrespondingly moves a truing tool 27 toward and from the grindingwheel ll. As shown in Figure 4, the truing tool 27 is mounted on the endof a cylindrical support 28, which is slidably mounted in a housing 29,for adjustment by a screw 30 threaded in a nut member 31 secured to theend of the member 28 by suitable screws 32. The screw 39 is anchored inthe end of the member 29 against axial movement by a suitable rib 33 andis provided with a hand wheel 34 and suitably graduated dial 35 foreffecting the necessary adjustments of the support 28. A set screw 36mounted in the member 29 projects into a spline 37 formed in. theperiphery of the member 28 to prevent rotation thereof. p

As shown in Figure 2, the housing 29 is supported on opposite sides byanti-friction bearings 38 and 39 in a supporting housing 40. Thishousing 40, as shown in Figure 4, is slidably supported by bearingsurfaces 41 and 42, and guide'surfaces 43 and 44 formed on the top of abracket, indicated generally by the reference numeral 45 and attached at46 to a fixed part 47 of the machine.

The housing 29 has a cylinder 48 formed integral therewith as shown inFigure 4, and this cylinder contains a piston 49 from which piston rods50 and 51 extend in opposite directions and are connected at oppositeends to the housing 40. From this construction it will be noted that thepiston 49 is held against move ment by its connections to the housing40, and therefore the cylinder 48 and member 29 constitute the movingelements in moving the truing tool toward and from the grinding wheel.

In order to traverse the truing tool across the face of the grindingweel 11 as shown in Figure 2, the housing 40 is connected by a pistonrod 52 to a piston 53 contained in a cylinder 54. The cylinder isattached to one end of the fixed bracket 45. It will now be seen thatthe piston and cylinder 53, 54 effect traverse of the truing tool acrossthe face of the Wheel, and the cylinder, piston 48, 49 effect movementof the truing tool toward and from the grinding wheel. As shown inFigures 3 and 4, the template 22, which is a removable item, and othertemplates may be substituted therefor, is clamped by a clamping shoe 55to a fixed part 56 of the housing 40. The follower 26 is attached byscrews 57 to the member 29. It will now be seen, as shown in Figure 4,that the follower 26 will move with the slide 40 across the wheel andwill be moved with the truing toolsupport 29 toward and from thegrinding wheel.

Fluid pressure is supplied to the cylinders 48 and 54 by a pump 57,Figure 5, having a relief valve 58. The delivery from the pump 57 isconnected by channel 59 to port 60 of a start and stop valve 61. Thisvalve has an exhaust port 62 which is connected by channel 63 to a lowpressure relief valve 64 which is set just high enough to maintain fluidin the system. The start and stop valve has a plunger 65 in which isformed a valve groove 66 which is of such width that in one positionsuch as shown it will close the port 60 and open the port 62 and therebyconnect it to the outgoing port 67, or in the up position of the plunger65 the port 62 will be closed and the port 67 connected to the pressureport 60 whereby fluid will now be delivered to channel 68. The plunger65 is adapted to be actuated automatically by an electric solenoid 69.

The pressure channel 68 has a branch connection 70 to port 71 of .areversing valve 72 for the traversing cylinder 54. This valve has ports73 and 74 which are connected by channels 75 and 76 to ports 77 and 78located in opposite ends of the cylinder 54. The valve also returnsports 75 and 76 which are connected to a return line 77. The valveplunger 78' of the valve 72 is a conventional reversing valve plungerhaving grooves 79 and 80 for reversing the flow to the cylinder 54. Thisplunger is adapted to be shifted in opposite directions by electricsolenoids 81 and 82, which are connected by piston rods 83 and 84 toopposite ends of the valve plunger. It will now be seen that dependentupon the position of the valve plunger 78' the piston 53 will be movedforward or backward to reciprocate the housing 40 carrying the follower26 parallel to the face of the grinding wheel 11. When the follower 26engages a steep rise or a perpendicular shoulder the resistance tomovement of the slide 40 will increase, and means have been providedwhich are responsive to changes in resistance to automaticallydifferentiate the pressures on opposite sides of the piston 49 to effecta boost to the movement of the follower 26 whenever it meets too great aresistance and is therefore unable to follow the template.

To this end the opposite ends of the cylinder 48 is connected bychannels 85 and 86 to a second reversing valve 87 which may be termed areaction valve. This valve has ports 88 and 89 to which the pressureline 68 from the pump is connected.

It also has a center port 90 which is connected to the return line 77from the reversing valve '72 for the traversing slide. Between the ports89 and 90 is a port 91 to which the line 86 is connected, and betweenthe ports 90 and 88 is a port 92 to which the line 85 is connected. Thevalve plunger 93 has annular grooves 94 and 95 which are slightlygreater in Width than the spacing between ports 89 and 90, and 90 and88, to permit a small predetermined center flow from the ports 88 and 89which are at the higher pressure, that is, of the pump, to the port 90which is at a lower pressure. When the valve plunger 93 is in a centerposition the lines 85 and 86 and the opposite ends of the cylinder 48are filled with fluid pressure, all at equal pressure so that the piston49 is held stationary.

The line 77', which is the return line from the traversing cylinder 54,is connected by channel 96 to a pres sure reducing valve 97 having aport 98 which is throttled by the taper spool 99 on the valve plunger100. The valve 97 has a port 101 which is in constant communication withthe annular groove 102 in the plunger 100, and connected by channel 103to a throttle valve 104 having a return line 105, going to the lowpressure relief valve 64. It should now be evident that the traversingcylinder 54 is supplied by the pump 57 through the reverse valve 72, andthat the rate of movement of its piston 53 is controlled by the trottlevalve 104 placed in the return line from the cylinder whereby theforward pressure on the piston 53 is always a constant pressure asdetermined by the relief valve 58.

The reaction valve 87 has a port 106 at one end connected by channel 107to the pump line 68 whereby there is always a constant pressure actingon one end of the valve plunger 93 to shift it against the resistance ofan adjustable spring 108 mounted in the opposite end of the valvehousing. The plunger has an interdrilled passage 109 in one end whichconnects the annular groove 94 to the end chamber 110 containing thespring 108. Therefore, the constant pump pressure in the end chamber 111is opposed by the fluid pressure in chamber 110 plus the pressure of thespring 108. Normally, these are so adjusted that when the piston 53 isnot moving the valve plunger 93 will be in a center position.

Since it is obvious that a slight unbalance of the pressures in theopposite ends of the cylinder 48 are necessary to produce and maintain asmall force component on the follower 26 against the template 22 inorder that it will always maintain contact with the template, the

spring 108 is adjusted slightly to take care of this condition.

In the operation of the device there will be a constant forward pressureon the piston 53 to effect traverse of the slide and the pressure at thereturn port 78 and channel 76 will, of course, be lower than the forwardpressure dependent upon work load and the friction to be overcome. Solong as the work load and opposing friction, such as the frictionbetween the follower and template remain constant, the pressure dropacross the piston, 53 will remain constant, and the pressure at port 90of the reaction valve will be constant. If now the load increases causedby the follower encountering a sharp rise on the template 22 the backpressure in the return line 77 will drop, causing a drop in pressure atthe port 90 of the reaction valve. This will cause a drop in pressure inthe chambers 94 and 95 but a drop in pressure in the chamber 94 willcause a drop in pressure in the chamber 110, causingthe valve plunger 93to shift upward as viewed in Fig. 5. This will increase the opening ofport 89 and decrease the opening at port and since the pressure at theport 89 is greater than the pressure at the port 90, there will be aflow of fluid through the port 89 and thereby into the line 86 to shiftthe cylinder 48 and thereby the follower 26 away from the grinding wheeland cause it to rise against any surface that it is abutting.

Likewise, if the back pressure in line 77 should increase the pressuresin chambers 94 and of the reaction valve would rise, and the rise inpressure in chamber 94 would becommunicated to the chamber and causeshifting of the valve in a direction to close port 89 and open port 88..This would increase the pressure in line 85 and causemovement of thecylinder 19 and follower 26 toward the template. It will now be seenthat thereaction valve is sensitive to changes in load on the traversingpiston 53 caused either by increases or decreases in friction betweenthe follower 26 and the template 22, or by engagement of the followerwith a shoulder.

For automatic operation an electrical control circuit has been providedfor controlling actuation of the various solenoids, and, as shown inFigure 5, the solenoid 69 is connected to control switch 111, thesolenoid 81 is connected to the control switch 112, and the solenoid 82is connected to the control switch 113. One side of these switches isconnected by line 114 to one side of a transformer 115. Energization ofthe other side of the circuit is partially controlled by a pressureswitch 116 having a channel 117 connected to the pump line 68 wherebywhen the line is under full pressure, the pressure switch will be closedinterconnecting line 118 from one side of the transformer to line 119.

The switch 113 is operated by a relay 120 in series with a dog actuatedcontrol limit switch 121. Similarly, the switches 111 and 112 arecontrolled by a relay 122 operated by a limit switch 123. g

As shown in Figure 2, the limit switches 121 and 12.1 are suitablysecured in a T-slot 124 formed on the base 45 for trip operation bycontrol dogs 125 and 126 can ried by the cross slide 40. Normally, theslide 430 has a starting position such as that shown in Figure 2 to theleft of the grinding wheel 11, as viewed in that figure, and it will benoted that the dog 126 is in a position to close the limit switch 123.With the control circuit energized and the pressure switch closed thiswould normally close switches 111 and 112 and thereby energize solenoids69 and 81. The energization of solenoid 69, however, shifts the stopvalve 61 to a stop position. Therefore, to start the cycle the operatoractuates the starting switch 127 which breaks the circuit to thesolenoid 69 whereby the operator by means of the lever 128 can manuallyshift the stop valve to a running position. As soon as the table startsto move and the dog 126 has released the limit switch 123,the operatormay release the starting button 127 whereby the circuit is set up forthe next cycle, but the switches 111 and 112 will open, and the slidemovement will continue.

When the dog 125 actuates the limit switch 121 and closes the circuit tothe relay 120, the switch 113 will be closed to energize the solenoid 82and shift the reversing valve 78 which will cause hydraulic reversal ofthe slide. This reversal will cause the dog 125 to leave the limitswitch 121 whereby the switch 113 will open but the reversing valve willstill remain in the same position. At the end of the return stroke thelimit switch 123 will again be operated, and this time will causereversal of the valve 78 but will also actuate the stop valve to cut offthe flow of fluid to the cylinder whereby the slide will stop. If it isdesired that the cycle continue, the operator merely presses thestarting button 127 whereby upon reversal the solenoid 69 will not beactuated, and

so the table will reverse and continue through another cycle.

Attention is invited to the fact that where the shape of the template isstraight that it may be desirable to have a faster rate of movement ofthe diamond relative to such portions, and therefore means have beenprovided for increasing the rate of movement independent of the settingof the rate throttle valve 104-. This is accomplished by providing aby-pass valve, or it may be designated a rapid feed valve 123 which. hasan inlet port 129 connected by a branch line 130 to the return line 96leading to the pressure reducing valve 97. This valve has a plunger 131which is normally held in the position shown by a spring 132 so that anannular groove 133 formed in the valve body will be in position to closethe port 129 and open the port 134 which is connected by a by-pass line135 to channel 105 whereby when the plunger 131 is depressed the ports129 and 134 will be interconnected and the returning fluid throughchannel 96 will be directly bypassed to line 105 without going throughthe throttle valve 104. The plunger 131 has an extension 136 and thevalve is so positioned in the T-slot 124 of the base of the machine thatit will engage a template 137 mounted in the T-slot 138 of thetraversing slide 40. By proper shape of contour 139 of the template 137the valve 128 may be operated'as desired during the stroke of thetraveling slide.

There has thus been provided a new and improved apparatus which makespossible the use of a template to control the movement of a truing tooltoward and from a grinding wheel to profile the same regardless of sharpangles or turns in the shape of the profile. The booster mechanismoperates to help withdrawal and to effect advance of the tool, and themechanism is operative regardless of which direction the tool istraversed across the wheel. 1

What is claimed is:

1. In a truing device having a traversible slide mounted on a support, across slide carrying a truing tool mounted on the traversible slide formovement normal to the direction of movement of the traversible slide, atemplate mounted on said support, a follower mounted on the cross slidein engagement with said template, the combination of hydraulic means forfeeding the traversible slide, means to hydraulically bias said crossslide to maintain engagement of said follower with said template andcreate a normal frictional load on said hydraulic feeding means, andmeans responsive to variation in said load to vary said bias and causemovement of the cross slide in a direction to reestablish said normalload. 1

2. In a truing device having a traversible slide mounted on a grindingwheel support, a cross slide mounted on the traversible slide andcarrying a truing tool for movement normal to the direction of movementof the traversible slide, the combination of opposed hydraulic pressuremeans for holding the cross slide eperatively in engagement with atemplate carried by said support, hydraulic means for feeding thetraversible slide, means to bias said opposed pressures including areaction valve operatively connected to control said opposed hydraulicpressures, and means responsive to a change in load on said hydraulicfeeding means to shift said valve.

3. In a truing device having a traversible slide mounted on a support, across slide carrying a truing tool mounted on the traversible slide formovement normal to the direction of movement of the traversible slide, afixed template carried by said support and extending parallel to saidtraversible slide, a follower carried by the cross slide andfrictionally engaging said template, the combination of hydraulicallyactuated means for feeding the traversible slide including a rate valvefor maintaining a back pressure on said actuated means, opposedhydraulic means effective on said cross slide for maintaining engagementof the follower with the template whereby when the follower engages ashoulder on the template the load on said traversible slide is increasedand the back pressure drops, and means responsive to said drop inpressure for biasing said opposed pressures.

4. A truing device having a traversible slide mounted on a fixedsupport, a feed cylinder mounted on said fixed support and operativelyconnected to said traversible slide, said feed cylinder having pressureand return lines, a throttle in said return line for creating a backpressure in said line to control the rate of move ment of thetraversible slide, a cross slide mounted on the traversible slide formovement normal to the di rection of movement of the traversible slide,a follower mounted on the cross slide in engagement with a templatemounted on the fixed support, means to hydraulically bias said crossslide to maintain engagement of said follower with said template, andmeans responsive to changes in pressure in said return line for varyingthe bias of said hydraulic means.

5. In a truing device having a traversible slide mounted on a support, across slide mounted on the traversible slide for movement normal to thedirection of movement of the traversible slide, a truing tool carried bythe cross slide, a template and follower, one of which is mounted onsaid support, and the other on the cross slide, the combination ofhydraulic means for feeding the traversible slide including a reversevalve having a return line, a rate valve in said return line causingback pressure therein, biased hydraulic pressure means operativelyconnected to said cross slide for maintaining frictional contact of saidfollower with said template and create a load on said feeding meansWhereby a substantial change in said load will produce a change in saidback pressure, and means actuable in response to a change in said backpressure to change the bias of said hydraulic pressure means.

6. In a truing device having a traversible slide mounted on a support, across slide guided on the traversible slide for movement normal to thedirection of movement of the traversible slide, a truing tool on thecross slide, a template mounted on said support, a follower mounted onthe cross slide, the combination of hydraulic means for feeding thetraversible slide including a reverse valve having a return line, a ratevalve in said return line causing back pressure in said line, a pistonand cylinder operatively connected to said cross slide, means to connectpressure to opposite sides of said piston including a reaction valve fordifferentiating the pressures on opposite sides of said piston for main:taining frictional contact of said follower with said template andcreate a load on said feeding means whereby a substantial change in saidload will-produce a change in said back pressure, and means connectingsaid back pressure to said reaction valve to cause movement thereof inresponse to changes in said back pressure.

7. A truing device having a traversible slide mounted on a fixedsupport, 'a feed cylinder mounted on said fixed support and operativelyconnected to said traversible slide, said feed cylinder having pressureand return lines, a throttle in said return line for creating a backpressure therein to control the rate of movement of the traversibleslide, a cross'slide mounted on the traversible slide for movement in adirection normal thereto, a follower mounted on the cross slide inengagement with a template mounted on the fixed support, means tohydraulically bias said cross slide to maintain engagement of saidfollower with said template, means responsive to pressure changes insaid return line for varying the bias of said hydraulic means, andautomatically controlled means to bypass said throttle valve to effect afaster rate of movement of the traversible slide.

8. In a truing device having a traversible slide mounted on a support, across slide carrying a truing tool mounted on the traversible slide formovement normal to the direction of movement of the traversible slide, atemplate mounted on said support, a follower mounted on the cross slidein engagement with said template, the combination of hydraulic means forfeeding the traversible slide including a reverse valve having a returnline, trip operable electrical means for shifting said reverse valve,biased hydraulic pressure means operatively connected to said crossslide for maintaining frictional contact of said follower with saidtemplate and create a load on said feeding means whereby a substantialchange in said load will produce a change in said back pressure, meansactuable in response to a change in said back pressure to change thebias of said hydraulic pressure means, and trip dogs carried by saidtraveling slide for operation of said trip operable means.

9. In a truing device having a traversible slide mounted on a grindingwheel support, a cross slide mounted on the traversible slide formovement normal to the direction of movement of the traversible slide, atruing tool carrier mounted on said cross slide, means to adjust saidcarrier relative to the cross slide, the combination of opposedhydraulic pressure means for holding the cross slide operatively inengagement with a template carried by said support, hydraulic means forfeeding the traversible slide,means to bias said opposed pressuresincluding a reaction valve operatively connected to control said opposedpressures, and means responsive to a change in load on said hydraulicfeeding means to shift said reaction valve.

No references cited.

